The invention relates to a locking device for preventing the simultaneous displacement of two slides movable in a common plane, in particular for two slides each associated with a respective one of two push buttons, each slide being associated with a return spring and being provided with a ramp and with a notch which are both directed towards a same bolt which is placed between them and which is capable of being displaced, when one of the push buttons is actuated, into a working position in which this bolt prevents the displacement of the other push button.
Such devices are particularly used to avoid short circuits which can arise during the excitation of a motor, for example that of a lifting motor, during the period of reversal of the direction of rotation.